Lubrication oil compositions

ABSTRACT

This invention relates to compositions comprising (i) a base fluid stock comprising (a) a PTEEG fluid (a poly(trimethylene-ethylene ether)glycol that is a fluid at ambient temperature) and (b) an additive package comprising certain specified additive combinations, and lubrication oils containing the compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to commonly owned U.S. application Ser. No. 11/593,954, filed Nov. 7, 2006, entitled “POLYTRIMETHYLENE ETHER GLYCOL ESTERS”; commonly owned U.S. Provisional Application Ser. No. 60/957,716, filed concurrently herewith, entitled “LUBRICATION OIL COMPOSITIONS”; commonly owned U.S. Provisional Application Ser. No. 60/957,725, filed concurrently herewith, entitled “LUBRICATION OIL COMPOSITIONS” (Internal Reference CL3886); and commonly owned U.S. Provisional Application Ser. No. 60/957,722, filed concurrently herewith, entitled “LUBRICATION OIL COMPOSITIONS” (Internal Reference CL3887).

FIELD OF THE INVENTION

This invention relates compositions comprising (i) a poly(trimethylene-ethylene ether)glycol and (ii) an additive package comprising certain specified additive combinations, and lubrication oils containing the compositions.

BACKGROUND

Certain polytrimethylene ether glycols (“PO3Gs”), including but not limited to poly(trimethylene-ethylene ether)glycols, and mono- and diesters thereof (“PO3G esters”), have properties that make them useful in a variety of fields, including as lubricants, as disclosed in commonly owned U.S. Pat. No. 7,179,769 and U.S. application Ser. No. 11/593,954, filed Nov. 7, 2006, entitled “POLYTRIMETHYLENE ETHER GLYCOL ESTERS”.

Because of these properties, it is desirable to formulate lubricant compositions based on PO3Gs and PO3G esters.

SUMMARY OF THE INVENTION

The present invention is directed to compositions based on combinations of a specific type of PO3G (a poly(trimethylene-ethylene ether) glycol—PTEEG) with specific additive combinations, which compositions have properties making them especially suited for lubrication end uses.

In one embodiment, there is provided a lubrication oil composition comprising (i) a base fluid stock comprising a PTEEG that is fluid at ambient temperature, and (ii) an additive package comprising:

(a) an antiwear additive package comprising from about 0.5 to about 2.0 wt % (based on total composition weight) of a mixture comprising an amine phosphate antiwear additive and a phosphorothionate antiwear additive, and

(b) from about 0.1 to about 0.5 wt. % (based on total composition weight) of an additive that functions as an extreme pressure additive, as an antioxidant additive, or as an extreme pressure additive and an antioxidant additive. In preferred embodiments the additive that functions as an extreme pressure additive, as an antioxidant additive, or as an extreme pressure additive and an antioxidant additive. Is a methylene bis(dialkyldithiocarbamate)

When the PTEEG is based on biologically produced 1,3-propanediol, lubricant compositions with a very high renewable content can be provided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

Except where expressly noted, trademarks are shown in upper case.

Unless stated otherwise, all percentages, parts, ratios, etc., are by weight.

When an amount, concentration, or other value or parameter is given as either a range, preferred range or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range.

When the term “about” is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to.

As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Use of “a” or “an” are employed to describe elements and components of the invention. This is done merely for convenience and to give a general sense of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

The materials, methods, and examples herein are illustrative only and, except as specifically stated, are not intended to be limiting. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

Base Fluid Stock

As indicated above, the base fluid stock for use in the lubrication oil compositions of the present invention comprises a PTEEG that is a fluid at ambient temperature (25° C.). The base fluid stock may also comprise other natural and/or synthetic fluid co-lubricants.

Examples of natural fluid co-lubricants include vegetable oil-based lubricants, which are generally derived from plants and are generally composed of triglycerides. Normally, these are liquid at room temperature. Although many different parts of plants may yield oil, in actual practice oil is generally extracted primarily from the seeds of oilseed plants. These oils include both edible and inedible oils, and include, for example, high oleic sunflower oil, rapeseed oil, soybean oil, castor oil and the like, as well as modified oils such as disclosed in U.S. Pat. No. 6,583,302 (fatty acid esters) and I. Malchev, “Plant-Oil-Based Lubricants” (available from the Department of Plant Agriculture, Ontario Agriculture College, University of Guelph, 50 Stone Road W., Guelph, Ontario, Canada N1G 2W1).

Synthetic fluid co-lubricants (other than the PO3G and PO3G esters) include lubricating oils such as hydrocarbon oils such as polybutylenes, polypropylenes, propylene-isobutylene copolymers; polyoxyalkylene glycol polymers (other than PO3G) and their derivatives such as ethylene oxide and propylene oxide copolymers; and esters of dicarboxylic acids with a variety of alcohols such as dibutyl adipate, di(2ethylhexyl)sebacate, di-hexyl fumarate, dioctyl sebacate, diisoctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, and the 2-ethylhexyl diester of linoleic acid dimer.

PO3Gs other than PTEEGs, as well as PO3G esters generally (including but not limited to esters of PTEEGs), can be used as synthetic fluid co-lubricants as well.

Preferably, the base stock comprises a predominant amount of PTEEG (greater than 50 wt % based on the weight of the base stock). In some embodiments, the base stock can comprise the PTEEG in an amount of about 66 wt % or greater, or about 75 wt % or greater, or about 90 wt % or greater, or about 95 wt % or greater, based on the total weight of the base fluid stock. In some preferred embodiments, the base fluid stock comprises only (or substantially only) the PTEEG.

A portion of the PTEEG can be replaced with a PTEEG ester, and the amounts referred to above can be for the combination of PTEEG plus PTEEG ester. In one embodiment, the weight ratio of PTEEG/PTEEG ester in the base fluid stock is 1:1 or greater, or greater than 1:1 (the PTEEG being the predominant component), or about 1.5:1 or greater, or about 2:1 or greater, or about 5:1 or greater, or about 20:1 or greater. Also, the weight ratio is preferably about 25:1 or less, or about 20:1 or less, or about 10:1 or less.

The lubrication oil composition preferably comprises the base oil stock in an amount of about 50 wt % or greater, based on the total weight of the lubrication oil composition. In various embodiments, the lubrication oil can comprise the base stock in an amount of about 75 wt % or greater, or about 90 wt % or greater, or about 95 wt % or greater, based on the total weight of the lubrication oil composition.

Polytrimethylene Ether Glycol (PO3G) Generally

PO3G for the purposes of the present invention (including PTEEG) is an oligomeric or polymeric ether glycol in which at least 50% of the repeating units are trimethylene ether units.

PO3G is preferably prepared by polycondensation of monomers comprising 1,3-propanediol, preferably in the presence of an acid catalyst, thus resulting in polymers or copolymers containing —(CH₂CH₂CH₂O)— linkage (e.g, trimethylene ether repeating units). As indicated above, at least 50% of the repeating units are trimethylene ether units.

When a sulfur-based acid catalyst is utilized (such as sulfuric acid) to prepare the PO3G, the resulting product preferably contains less than about 20 ppm, more preferably less than about 10 ppm, of sulfur.

In addition to the trimethylene ether units, lesser amounts of other units, such as other polyalkylene ether repeating units, may be present. In the context of this disclosure, the term “polytrimethylene ether glycol” encompasses PO3G made from essentially pure 1,3-propanediol, as well as those oligomers and polymers (including PTEEG and others described below) containing up to about 50% by weight of comonomers.

For PTEEG, the other polyalkylene ether repeating units are predominantly ethylene ether units.

The 1,3-propanediol employed for preparing the PO3G may be obtained by any of the various well known chemical routes or by biochemical transformation routes. Preferred routes are described in, for example, U.S. Pat. No. 5,015,789, U.S. Pat. No. 5,276,201, U.S. Pat. No. 5,284,979, U.S. Pat. No. 5,334,778, U.S. Pat. No. 5,364,984, U.S. Pat. No. 5,3649,87, U.S. Pat. No. 5,633,362, U.S. Pat. No. 5,686,276, U.S. Pat. No. 5,821,092, U.S. Pat. No. 5,962,745, U.S. Pat. No. 6,140,543, U.S. Pat. No. 6,232,511, U.S. Pat. No. 6,235,948, U.S. Pat. No. 6,277,289, U.S. Pat. No. 6,297,408, U.S. Pat. No. 6,331,264, U.S. Pat. No. 6,342,646, U.S. Pat. No. 7,038,092, U.S. Pat. No. 7,084,311, U.S. Pat. No. 7,098,368, U.S. Pat. No. 7,009,082 and US20050069997A1. Preferably, the 1,3-propanediol is obtained biochemically from a renewable source (“biologically-derived” 1,3-propanediol).

A particularly preferred source of 1,3-propanediol is via a fermentation process using a renewable biological source. As an illustrative example of a starting material from a renewable source, biochemical routes to 1,3-propanediol (PDO) have been described that utilize feedstocks produced from biological and renewable resources such as corn feed stock. For example, bacterial strains able to convert glycerol into 1,3-propanediol are found in the species Klebsiella, Citrobacter, Clostridium, and Lactobacillus. The technique is disclosed in several publications, including U.S. Pat. No. 5,633,362, U.S. Pat. No. 5,686,276 and U.S. Pat. No. 5,821,092. U.S. Pat. No. 5,821,092 discloses, inter alia, a process for the biological production of 1,3-propanediol from glycerol using recombinant organisms. The process incorporates E. coli bacteria, transformed with a heterologous pdu diol dehydratase gene, having specificity for 1,2-propanediol. The transformed E. coli is grown in the presence of glycerol as a carbon source and 1,3-propanediol is isolated from the growth media. Since both bacteria and yeasts can convert glucose (e.g., corn sugar) or other carbohydrates to glycerol, the processes disclosed in these publications provide a rapid, inexpensive and environmentally responsible source of 1,3-propanediol monomer.

The biologically-derived 1,3-propanediol, such as produced by the processes described and referenced above, contains carbon from the atmospheric carbon dioxide incorporated by plants, which compose the feedstock for the production of the 1,3-propanediol. In this way, the biologically-derived 1,3-propanediol preferred for use in the context of the present invention contains only renewable carbon, and not fossil fuel-based or petroleum-based carbon. The PO3Gs based thereon utilizing the biologically-derived 1,3-propanediol, therefore, have less impact on the environment as the 1,3-propanediol used in the compositions does not deplete diminishing fossil fuels and, upon degradation, releases carbon back to the atmosphere for use by plants once again. Thus, the compositions of the present invention can be characterized as more natural and having less environmental impact than similar compositions comprising petroleum based glycols.

The biologically-derived 1,3-propanediol, PO3G and PO3G esters, may be distinguished from similar compounds produced from a petrochemical source or from fossil fuel carbon by dual carbon-isotopic finger printing. This method usefully distinguishes chemically-identical materials, and apportions carbon in the copolymer by source (and possibly year) of growth of the biospheric (plant) component. The isotopes, ¹⁴C and ¹³C, bring complementary information to this problem. The radiocarbon dating isotope (¹⁴C), with its nuclear half life of 5730 years, clearly allows one to apportion specimen carbon between fossil (“dead”) and biospheric (“alive”) feedstocks (Currie, L. A. “Source Apportionment of Atmospheric Particles,” Characterization of Environmental Particles, J. Buffle and H. P. van Leeuwen, Eds., 1 of Vol. I of the IUPAC Environmental Analytical Chemistry Series (Lewis Publishers, Inc) (1992) 3-74). The basic assumption in radiocarbon dating is that the constancy of ¹⁴C concentration in the atmosphere leads to the constancy of ¹⁴C in living organisms. When dealing with an isolated sample, the age of a sample can be deduced approximately by the relationship:

t=(−5730/0.693)ln(A/A ₀)

wherein t=age, 5730 years is the half-life of radiocarbon, and A and A₀ are the specific ¹⁴C activity of the sample and of the modern standard, respectively (Hsieh, Y., Soil Sci. Soc. Am J., 56, 460, (1992)). However, because of atmospheric nuclear testing since 1950 and the burning of fossil fuel since 1850, ¹⁴C has acquired a second, geo-chemical time characteristic. Its concentration in atmospheric CO₂, and hence in the living biosphere, approximately doubled at the peak of nuclear testing, in the mid-1960s. It has since been gradually returning to the steady-state cosmogenic (atmospheric) baseline isotope rate (¹⁴C/¹²C) of ca. 1.2×10⁻¹², with an approximate relaxation “half-life” of 7-10 years. (This latter half-life must not be taken literally; rather, one must use the detailed atmospheric nuclear input/decay function to trace the variation of atmospheric and biospheric ¹⁴C since the onset of the nuclear age.) It is this latter biospheric ¹⁴C time characteristic that holds out the promise of annual dating of recent biospheric carbon. ¹⁴C can be measured by accelerator mass spectrometry (AMS), with results given in units of “fraction of modern carbon” (f_(M)). f_(M) is defined by National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) 4990B and 4990C, known as oxalic acids standards HOxI and HOxII, respectively. The fundamental definition relates to 0.95 times the ¹⁴C/¹²C isotope ratio HOxI (referenced to AD 1950). This is roughly equivalent to decay-corrected pre-Industrial Revolution wood. For the current living biosphere (plant material), f_(M)≈1.1.

The stable carbon isotope ratio (¹³C/¹²C) provides a complementary route to source discrimination and apportionment. The ¹³C/¹²C ratio in a given biosourced material is a consequence of the ¹³C/¹²C ratio in atmospheric carbon dioxide at the time the carbon dioxide is fixed and also reflects the precise metabolic pathway. Regional variations also occur. Petroleum, C₃ plants (the broadleaf), C₄ plants (the grasses), and marine carbonates all show significant differences in ¹³C/¹²C and the corresponding δ ¹³C values. Furthermore, lipid matter of C₃ and C₄ plants analyze differently than materials derived from the carbohydrate components of the same plants as a consequence of the metabolic pathway. Within the precision of measurement, ¹³C shows large variations due to isotopic fractionation effects, the most significant of which for the instant invention is the photosynthetic mechanism. The major cause of differences in the carbon isotope ratio in plants is closely associated with differences in the pathway of photosynthetic carbon metabolism in the plants, particularly the reaction occurring during the primary carboxylation, i.e., the initial fixation of atmospheric CO₂. Two large classes of vegetation are those that incorporate the “C₃” (or Calvin-Benson) photosynthetic cycle and those that incorporate the “C₄” (or Hatch-Slack) photosynthetic cycle. C₃ plants, such as hardwoods and conifers, are dominant in the temperate climate zones. In C₃ plants, the primary CO₂ fixation or carboxylation reaction involves the enzyme ribulose-1,5-diphosphate carboxylase and the first stable product is a 3-carbon compound. C₄ plants, on the other hand, include such plants as tropical grasses, corn and sugar cane. In C₄ plants, an additional carboxylation reaction involving another enzyme, phosphenol-pyruvate carboxylase, is the primary carboxylation reaction. The first stable carbon compound is a 4-carbon acid, which is subsequently decarboxylated. The CO₂ thus released is refixed by the C₃ cycle.

Both C₄ and C₃ plants exhibit a range of ¹³C/¹²C isotopic ratios, but typical values are ca. −10 to −14 per mil (C₄) and −21 to −26 per mil (C₃) (Weber et al., J. Agric. Food Chem., 45, 2942 (1997)). Coal and petroleum fall generally in this latter range. The ¹³C measurement scale was originally defined by a zero set by pee dee belemnite (PDB) limestone, where values are given in parts per thousand deviations from this material. The “δ¹³C” values are in parts per thousand (per mil), abbreviated %, and are calculated as follows:

${\delta^{13}C} \equiv {\frac{{\left( {{\,^{13}C}/{\,^{12}C}} \right)\mspace{14mu} {sample}} - {\left( {{\,^{13}C}/{\,^{12}C}} \right)\mspace{14mu} {standard}}}{\left( {{\,^{13}C}/{\,^{12}C}} \right)\mspace{14mu} {standard}} \times 1000\%}$

Since the PDB reference material (RM) has been exhausted, a series of alternative RMs have been developed in cooperation with the IAEA, USGS, NIST, and other selected international isotope laboratories. Notations for the per mil deviations from PDB is δ¹³C. Measurements are made on CO₂ by high precision stable ratio mass spectrometry (IRMS) on molecular ions of masses 44, 45 and 46.

Biologically-derived 1,3-propanediol, and compositions comprising biologically-derived 1,3-propanediol, therefore, may be completely distinguished from their petrochemical derived counterparts on the basis of ¹⁴C (f_(M)) and dual carbon-isotopic fingerprinting, indicating new compositions of matter. The ability to distinguish these products is beneficial in tracking these materials in commerce. For example, products comprising both “new” and “old” carbon isotope profiles may be distinguished from products made only of “old” materials. Hence, the instant materials may be followed in commerce on the basis of their unique profile and for the purposes of defining competition, for determining shelf life, and especially for assessing environmental impact.

Preferably the 1,3-propanediol used as the reactant or as a component of the reactant will have a purity of greater than about 99%, and more preferably greater than about 99.9%, by weight as determined by gas chromatographic analysis. Particularly preferred are the purified 1,3-propanediols as disclosed in U.S. Pat. No. 7,038,092, U.S. Pat. No. 7,098,368, U.S. Pat. No. 7,084,311 and US20050069997A1, as well as PO3G made therefrom as disclosed in US20050020805A1.

The purified 1,3-propanediol preferably has the following characteristics:

(1) an ultraviolet absorption at 220 nm of less than about 0.200, and at 250 nm of less than about 0.075, and at 275 nm of less than about 0.075; and/or

(2) a composition having L*a*b* “b*” color value of less than about 0.15 (ASTM D6290), and an absorbance at 270 nm of less than about 0.075; and/or

(3) a peroxide composition of less than about 10 ppm; and/or

(4) a concentration of total organic impurities (organic compounds other than 1,3-propanediol) of less than about 400 ppm, more preferably less than about 300 ppm, and still more preferably less than about 150 ppm, as measured by gas chromatography.

The starting material for making PO3G will depend on the desired PO3G, availability of starting materials, catalysts, equipment, etc., and comprises “1,3-propanediol reactant.” By “1,3-propanediol reactant” is meant 1,3-propanediol, and oligomers and prepolymers of 1,3-propanediol preferably having a degree of polymerization of 2 to 9, and mixtures thereof. In some instances, it may be desirable to use up to 10% or more of low molecular weight oligomers where they are available. Thus, preferably the starting material comprises 1,3-propanediol and the dimer and trimer thereof. A particularly preferred starting material is comprised of about 90% by weight or more 1,3-propanediol, and more preferably 99% by weight or more 1,3-propanediol, based on the weight of the 1,3-propanediol reactant.

PO3G can be made via a number of processes known in the art, such as disclosed in U.S. Pat. No. 6,977,291 and U.S. Pat. No. 6,720,459. The preferred processes are as set forth in U.S. Pat. No. 7,074,969, U.S. Pat. No. 7,157,607, U.S. Pat. No. 7,161,045 and U.S. Pat. No. 7,164,046.

As indicated above, PO3G may contain lesser amounts of other polyalkylene ether repeating units in addition to the trimethylene ether units. The monomers for use in preparing PO3G can, therefore, contain up to 50% by weight of comonomer polyols in addition to the 1,3-propanediol reactant. Comonomer polyols that are suitable for use in the process include aliphatic diols, for example, ethylene glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 3,3,4,4,5,5-hexafluro-1,5-pentanediol, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol, and 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10-hexadecafluoro-1,12-dodecanediol; cycloaliphatic diols, for example, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and isosorbide; and polyhydroxy compounds, for example, glycerol, trimethylolpropane, and pentaerythritol. A preferred group of comonomer diols is selected from the group consisting of ethylene glycol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol, C₆-C₁₀ diols (such as 1,6-hexanediol, 1,8-octanediol and 1,10-decanediol) and isosorbide, and mixtures thereof. A particularly preferred diol other than 1,3-propanediol is ethylene glycol, and C₆-C₁₀ diols can be particularly useful as well.

Suitable PTEEGs for use in the present invention are described, for example, in US20040030095A1. Preferred PTEEGs are prepared by acid catalyzed polycondensation of from 50 to about 99 mole % (preferably from about 60 to about 98 mole %, and more preferably from about 70 to about 98 mole %) 1,3-propanediol and up to 50 to about 1 mole % (preferably from about 40 to about 2 mole %, and more preferably from about 30 to about 2 mole %) ethylene glycol.

Preferably, the PTEEG after purification has essentially no acid catalyst end groups, but may contain very low levels of unsaturated end groups, predominately allyl end groups, in the range of from about 0.003 to about 0.03 meq/g. Such a PTEEG can be considered to comprise (consist essentially of) the compounds having the following formulae (I) and (II):

HO—((CH₂)₃O)_(m)((CH₂)₂O)_(n)—H   (I)

HO—((CH₂)₃—O)_(m)((CH₂)₂O)_(n)CH₂CH═CH₂   (II)

wherein m and n are in a range such that the Mn (number average molecular weight) is within the range of from about 200 to about 10000, with compounds of formula (III) being present in an amount such that the allyl end groups (preferably all unsaturation ends or end groups) are present in the range of from about 0.003 to about 0.03 meq/g.

The PTEEGs can be random or block copolymers, and formulas (I) and (II) are intended to cover both varieties.

The preferred PO3G (including PTEEG) for use in the invention has an Mn (number average molecular weight) of at least about 250, more preferably at least about 1000, and still more preferably at least about 2000. The Mn is preferably less than about 10000, more preferably less than about 5000, and still more preferably less than about 3500. Blends of PO3Gs can also be used. For example, the PO3G can comprise a blend of a higher and a lower molecular weight PO3G, preferably wherein the higher molecular weight PO3G has a number average molecular weight of from about 1000 to about 5000, and the lower molecular weight PO3G has a number average molecular weight of from about 200 to about 950. The Mn of the blended PO3G will preferably still be in the ranges mentioned above.

PO3G preferred for use herein is typically polydisperse having a polydispersity (i.e. Mw/Mn) of preferably from about 1.0 to about 2.2, more preferably from about 1.2 to about 2.2, and still more preferably from about 1.5 to about 2.1. The polydispersity can be adjusted by using blends of PO3G.

PO3G for use in the present invention preferably has a color value of less than about 100 APHA, and more preferably less than about 50 APHA, and a viscosity which is preferably about 100 cS or greater at 40° C.

PO3G Esters

In some embodiments, the PO3G esters comprise one or more compounds of the formula (III):

wherein Q represents the residue of a PO3G after abstraction of the hydroxyl groups, R₂ is H or R₃CO, and each of R₁ and R₃ is individually a substituted or unsubstituted aromatic, saturated aliphatic, unsaturated aliphatic or cycloaliphatic organic group, containing from 4 to 40 carbon atoms, preferably at least 6 carbon atoms, more preferably at least 8 carbon atoms. In some embodiments each of R₁ and R₃ has 20 carbon atoms or fewer, and in some embodiments 10 carbon atoms or fewer. In some preferred embodiments, each of R₁ and R₃ has 8 carbon atoms.

PO3G esters are preferably prepared by polycondensation of hydroxyl groups-containing monomers (monomers containing 2 or more hydroxyl groups) predominantly comprising 1,3-propanediol to form a PO3G (as disclosed above), followed by esterification with a monocarboxylic acid (or equivalent), as disclosed in U.S. application Ser. No. 11/593,954, filed Nov. 7, 2006, entitled “POLYTRIMETHYLENE ETHER GLYCOL ESTERS”.

The PO3G ester thus prepared is a composition preferably comprising from about 50 to 100 wt %, more preferably from about 75 to 100 wt %, diester and from 0 to about 50 wt %, more preferably from 0 to about 25 wt %, monoester, based on the total weight of the esters. Preferably the mono-and diesters are esters of 2-ethylhexanoic acid.

The PO3G used for preparing the ester need not be the same as the PO3G co-component of the base fluid stock.

Acid and Equivalents

The esterification of the PO3G is carried out by reaction with an acid and/or equivalent, preferably a monocarboxylic acid and/or equivalent.

By “monocarboxylic acid equivalent” is meant compounds that perform substantially like monocarboxylic acids in reaction with polymeric glycols and diols, as would be generally recognized by a person of ordinary skill in the relevant art. Monocarboxylic acid equivalents for the purpose of the present invention include, for example, esters of monocarboxylic acids, and ester-forming derivatives such as acid halides (e.g., acid chlorides) and anhydrides.

Preferably, a monocarboxylic acid is used having the formula R—COOH, wherein R is a substituted or unsubstituted aromatic, aliphatic or cycloaliphatic organic moiety containing from 6 to 40 carbon atoms.

Mixtures of different monocarboxylic acids and/or equivalents are also suitable.

As indicated above, the monocarboxylic acid (or equivalent) can be aromatic, aliphatic or cycloaliphatic. In this regard, “aromatic” monocarboxylic acids are monocarboxylic acids in which a carboxyl group is attached to a carbon atom in a benzene ring system such as those mentioned below. “Aliphatic” monocarboxylic acids are monocarboxylic acids in which a carboxyl group is attached to a fully saturated carbon atom or to a carbon atom which is part of an olefinic double bond. If the carbon atom is in a ring, the equivalent is “cycloaliphatic.”

The monocarboxylic acid (or equivalent) can contain any substituent groups or combinations thereof (such as functional groups like amide, amine, carbonyl, halide, hydroxyl, etc.), so long as the substituent groups do not interfere with the esterification reaction or adversely affect the properties of the resulting ester product.

The monocarboxylic acids and equivalents can be from any source, but preferably are derived from natural sources or are bio-derived.

The following acids and their derivatives are specifically preferred: lauric, myristic, palmitic, stearic, arachidic, benzoic, caprylic, erucic, palmitoleic, pentadecanoic, heptadecanoic, nonadecanoic, linoleic, arachidonic, oleic, valeric, caproic, capric and 2-ethylhexanoic acids, and mixtures thereof. Particularly preferred acids or derivatives thereof are 2-ethylhexanoic acid, benzoic acid, stearic acid, lauric acid and oleic acid.

Esterification Process

For preparation of the esters, the PO3G can be contacted, preferably in the presence of an inert gas, with the monocarboxylic acid(s) at temperatures ranging from about 100° C. to about 275° C., preferably from about 125° C. to about 250° C. The process can be carried out at atmospheric pressure or under vacuum. During the contacting water is formed is formed and can be removed in the inert gas stream or under vacuum to drive the reaction to completion.

To facilitate the reaction of PO3G with carboxylic acid an esterfication catalyst is generally used, preferably a mineral acid catalyst. Examples of mineral acid catalysts include but are not restricted to sulfuric acid, hydrochloric acid, phosphoric acid, hydriodic acid, and heterogeneous catalysts such as zeolites, heteropolyacid, amberlyst, and ion exchange resin. Preferred esterification acid catalysts are selected from the group consisting of sulfuric acid, phosphoric acid, hydrochloric acid and hydroiodic acid. A particularly preferred mineral acid catalyst is sulfuric acid.

The amount of catalyst used can be from about 0.01 wt % to about 10 wt % of the reaction mixture, preferably from 0.1 wt % to about 5 wt %, and more preferably from about 0.2 wt % to about 2 wt %, of the reaction mixture.

Any ratio of carboxylic acid, or derivatives thereof, to glycol hydroxyl groups can be used. The preferred ratio of acid to hydroxyl groups is from about 3:1 to about 1:2, where the ratio can be adjusted to shift the ratio of monoester to diester in the product. Generally to favor production of diesters slightly more than a 1:1 ratio is used. To favor production of monoesters, a 0.5:1 ratio or less of acid to hydroxyl is used.

A preferred method for esterification comprises polycondensing 1,3-propanediol reactant to PO3G using a mineral acid catalyst, then adding carboxylic acid and carrying out the esterification without isolating and purifying the PO3G. In this method, the etherification or polycondensation of 1,3-propanediol reactant to form PO3G is carried out using an acid catalyst as disclosed in U.S. Pat. No. 6,977,291 and U.S. Pat. No. 6,720,459. The etherification reaction may also be carried out using a polycondensation catalyst that contains both an acid and a base as described in JP2004-182974A. The polycondensation or etherification reaction is continued until desired molecular weight is reached, and then the calculated amount of monocarboxylic acid is added to the reaction mixture. The reaction is continued while the water byproduct is removed. At this stage both esterification and etherification reactions occur simultaneously. Thus, in this preferred esterification method the acid catalyst used for polycondensation of diol is also used for esterification. If necessary additional esterification catalyst can be added at the esterification stage.

In this procedure, the viscosity (molecular weight) of the resulting product is controlled by the point at which the carboxylic acid is added.

In an alternative procedure, the esterification reaction can be carried out on purified PO3G by addition of an esterification catalyst and carboxylic acid followed by heating and removal of water. In this procedure, viscosity of the resulting product is predominantly a function of the molecular weight of the PO3G utilized.

Regardless of which esterification procedure is followed, after the esterification step any by products are removed, and then the catalyst residues remaining from polycondensation and/or esterification are removed in order to obtain an ester product that is stable, particularly at high temperatures. This may be accomplished by hydrolysis of the crude ester product by treatment with water at about 80° C. to about 100° C. for a time sufficient to hydrolyze any residual acid esters derived from the catalyst without impacting significantly the carboxylic acid esters. The time required can vary from about 1 to about 8 hours. If the hydrolysis is carried out under pressure, higher temperatures and correspondingly shorter times are possible. At this point the product may contain diesters, monoesters, or a combination of diesters and monoesters, and small amounts of acid catalyst, unreacted carboxylic acid and diol depending on the reaction conditions. The hydrolyzed polymer is further purified to remove water, acid catalyst and unreacted carboxylic acid by the known conventional techniques such as water washings, base neutralization, filtration and/or distillation. Unreacted diol and acid catalyst can, for example, be removed by washing with deionized water. Unreacted carboxylic acid also can be removed, for example, by washing with deionized water or aqueous base solutions, or by vacuum stripping.

Hydrolysis is generally followed by one or more water washing steps to remove acid catalyst, and drying, preferably under vacuum, to obtain the ester product. The water washing also serves to remove unreacted diol. Any unreacted monocarboxylic acid present may also be removed in the water washing, but may also be removed by washing with aqueous base or by vacuum stripping.

If desired, the product can be fractionated further to isolate low molecular weight esters by a fractional distillation under reduced pressure.

Proton NMR and wavelength X-ray fluorescence spectroscopic methods can be used to identify and quantify any residual catalyst (such as sulfur) present in the polymer. The proton NMR can, for example, identify the sulfate ester groups present in the polymer chain, and wavelength x-ray fluorescence method can determine the total sulfur (inorganic and organic sulfur) present in the polymer. The esters of the invention made from the process described above are substantially sulfur free and thus useful for high temperature applications.

Preferably, the PO3G esters after purification have essentially no acid catalyst end groups, but may contain very low levels of unsaturated end groups, predominately allyl end groups, in the range of from about 0.003 to about 0.03 meq/g. Such PO3G ester can be considered to comprise (consist essentially of) the compounds having the following formulae (IV) and (V):

R₁—C(O)—O—((CH₂)₃O)_(m)((CH₂)₂O)_(n)—R₂   (IV)

R₁—C(O)—O—((CH₂)₃—O)_(m)((CH₂)₂O)_(n)CH₂CH═CH₂   (V)

wherein R₂ is H or R₃C(O); each of R₁ and R₃ is individually a substituted or unsubstituted aromatic, saturated aliphatic, unsaturated aliphatic, or cycloaliphatic organic group containing from 6 to 40 carbon atoms; m and n are in a range such that the Mn is within the range of from about 200 to about 10000; and with compounds of formula (III) being present in an amount such that the allyl end groups (preferably all unsaturation ends or end groups) are present in the range of from about 0.003 to about 0.03 meq/g.

Preferably, the PO3G ester has a viscosity which is less than the viscosity of PO3G. Preferred viscosities of PO3G esters range from about 20 cS to about 150 cS at 40° C., and more preferably are about 100 cS or less.

Other preferred properties of the PO3G esters can be determined based upon the preferences stated above for PO3G in and of itself. For example, preferred molecular weights and polydispersities are based on the preferred molecular weights and polydispersities of the PO3G component of the ester.

Additives in General

Synthetic lube oil compositions in accordance with the present invention comprise a mixture of the base stock and one or more additives, where each additive is employed for the purpose of improving the performance and properties of the base stock in its intended application, e.g., as a hydraulic fluid, a gear oil, a brake fluid, a compressor lubricant, a textile and calender lubricant, a metalworking fluid, a refrigeration lubricant, a two-cycle engine lubricant and/or crankcase lubricant.

The additives can generally be added in amounts based on the type of additive and desired level of additive effect, which can generally be determined by those skilled in the relevant art.

Preferably the additives are miscible in either or both of the PO3G and PO3G esters.

Preferably, the lube oil additive(s) comprise at least one of ashless dispersant, metal detergent, viscosity modifier, anti-wear agent, antioxidant, friction modifier, pour point depressant, anti-foaming agent, corrosion inhibitor, demulsifier, rust inhibitor and mixtures thereof.

When the lube oil composition is used as a refrigeration lubricant, the lube oil additive(s) preferably comprise at least one of extreme pressure and antiwear additive, oxidation and thermal stability improver, corrosion inhibitor, viscosity index improver, pour point depressant, floc point depressant, detergent, anti-foaming agent, viscosity adjuster and mixtures thereof.

It is intended to be within the scope of the present invention to use any one or more of the specified additives alone or in combination with one or more of the remaining specified additives. It is also within the scope of the present invention to use more than one of any specified additive, e.g., one or more friction modifiers, either alone or in combination of one or more of the other specified additives, e.g., in combination with one or more corrosion inhibitors.

The individual additives may be incorporated into a base stock in any convenient way. Thus, each of the components can be added directly to the base stock by dispersing or dissolving it in the base stock at the desired level of concentration. Such blending may occur at ambient temperature or at an elevated temperature.

Alternatively, all or some of the additives can be blended into a concentrate or additive package that is subsequently blended into base stock to make finished lubricant. The concentrate will typically be formulated to contain the additive(s) in proper amounts to provide the desired concentration in the formulation when the concentrate is combined with a predetermined amount of base lubricant.

Non-limiting, illustrative examples of various additives follow.

The ashless dispersant comprises a polymeric hydrocarbon backbone having functional groups that are capable of associating with particles to be dispersed. Typically, the dispersants comprise amine, alcohol, amide and/or ester polar moieties attached to the polymer backbone often via a bridging group. The ashless dispersant may be, for example, selected from salts, esters, amino-esters, amides, imides and oxazolines of long chain hydrocarbon substituted mono-and dicarboxylic acids and/or their anhydrides, thiocarboxylate derivatives of long chain hydrocarbons, long chain aliphatic hydrocarbons having a polyamine attached directly thereto, and Mannich condensation products formed by condensing a long chain substituted phenol with formaldehyde and polyalkylene polyamine.

The viscosity modifier (VM) functions to impart high and low temperature operability to a lubricating oil. The VM used may have that sole function, or may be multifunctional.

Multifunctional viscosity modifiers that also function as dispersants are also known. Illustrative viscosity modifiers are polyisobutylene, copolymers of ethylene and propylene and higher alpha-olefins, polymethacrylates, polyalkylmethacrylates, methacrylate copolymers, copolymers of an unsaturated dicarboxylic acid and a vinyl compound, inter polymers of styrene and acrylic esters, and partially hydrogenated copolymers of styrene/isoprene, styrene/butadiene, and isoprene/butadiene, as well as the partially hydrogenated homopolymers of butadiene and isoprene and isoprene/divinylbenzene.

Metal-containing or ash-forming detergents function both as detergents to reduce or remove deposits and as acid neutralizers or rust inhibitors, thereby reducing wear and corrosion and extending engine life. Detergents generally comprise a polar head with long hydrophobic tail, with the polar head comprising a metal salt of an acid organic compound. The salts may contain a substantially stoichiometric amount of the metal in which they are usually described as normal or neutral salts, and would typically have a total base number (TBN), as may be measured by ASTM D-2896 of from 0 to about 80. It is possible to include large amounts of a metal base by reacting an excess of a metal compound such as an oxide or hydroxide with an acid gas such as carbon dioxide. The resulting overbased detergent comprises neutralized detergent as the outer layer of a metal base (e.g., carbonate) micelle. Such overbased detergents may have a TBN of about 150 or greater, and typically from about 250 to about 450 or more.

Illustrative detergents include neutral and overbased sulfonates, phenates, sulfurized phenates, thiophosphonates, salicylates, and naphthenates and other oil-soluble carboxylates of a metal, particularly the alkali or alkaline earth metals, e.g., sodium, potassium, lithium, calcium, and magnesium. The most commonly used metals are calcium and magnesium, which may both be present in detergents used in a lubricant, and mixtures of calcium and/or magnesium with sodium. Particularly convenient metal detergents are neutral and overbased calcium sulfonates having TBN of from about 20 to about 450, and neutral and overbased calcium phenates and sulfurized phenates having TBN of from about 50 to about 450.

Dihydrocarbyl dithiophosphate metal salts are frequently used as anti-wear and antioxidant agents. The metal may be an alkali or alkaline earth metal, or aluminum, lead, tin, molybdenum, manganese, nickel or copper. The zinc salts are most commonly used in lubricating oil in amounts of from about 0.1 to about 10 wt %, preferably from about 0.2 to about 2 wt %, based upon the total weight of the lubricating oil composition. They may be prepared in accordance with known techniques by first forming a dihydrocarbyl dithiophosphoric acid (DDPA), usually by reaction of one or more alcohol or a phenol with P₂S₅ and then neutralizing the formed DDPA with a zinc compound. For example, a dithiophosphoric acid may be made by reacting mixtures of primary and secondary alcohols. Alternatively, multiple dithiophosphoric acids can be prepared where the hydrocarbyl groups on one are entirely secondary in character and the hydrocarbyl groups on the others are entirely primary in character. To make the zinc salt any basic or neutral zinc compound could be used but the oxides, hydroxides and carbonates are most generally employed. Commercial additives frequently contain an excess of zinc due to use of an excess of the basic zinc compound in the neutralization reaction.

In one embodiment, however, the lube oil compositions are preferably substantially zinc free.

Oxidation inhibitors or antioxidants reduce the tendency of base stocks to deteriorate in service which deterioration can be evidenced by the products of oxidation such as sludge and varnish-like deposits on the metal surfaces and by viscosity growth. Such oxidation inhibitors include hindered phenols, alkaline earth metal salts of alkylphenolthioesters having preferably C₅ to C₁₂ alkyl side chains, calcium nonylphenol sulfide, ashless oil soluble phenates and sulfurized phenates, phosphosulfurized or sulfurized hydrocarbons, phosphorous esters, metal thiocarbamates, oil-soluble copper compounds as described in U.S. Pat. No. 4,867,890, and molybdenum containing compounds.

Friction modifiers may be included to improve fuel economy. Oil-soluble alkoxylated mono-and di-amines are well known to improve boundary layer lubrication. The amines may be used as such or in the form of an adduct or reaction product with a boron compound such as boric oxide, boron halide, metaborate, boric acid or a mono-, di- or tri-alkyl borate.

Other friction modifiers are known. Among these are esters formed by reacting carboxylic acids and anhydrides with alkanols. Other conventional friction modifiers generally consist of a polar terminal group (e.g. carboxyl or hydroxyl) covalently bonded to an oleophilic hydrocarbon chain. Esters of carboxylic acids and anhydrides with alkanols are described in U.S. Pat. No. 4,702,850. An example of another conventional friction modifier is organo-metallic molybdenum.

Illustrative rust inhibitors are selected from the group of nonionic polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, and anionic alkyl sulfonic acids.

Copper and lead bearing corrosion inhibitors may also be used. Typically such compounds are the thiadiazole polysulfides containing from 5 to 50 carbon atoms, their derivatives and polymers thereof. Other additives are the thio- and polythio-sulfenamides of thiadiazoles such as those described in UK1560830. Benzotriazole derivatives also fall within this class of additives.

An illustrative example of demulsifying component is described in EP-A-0330522. It is obtained by reacting an alkylene oxide with an adduct obtained by reacting a bis-epoxide with a polyhydric alcohol.

Pour point depressants, otherwise known as lube oil improvers, lower the minimum temperature at which the fluid will flow or can be poured. Such additives are well known. Typical of those additives which improve the low temperature fluidity of the fluid are C₈ and C₁₈ dialkyl fumarate/vinyl acetate copolymers, polyalkylmethacrylates and the like.

Foam control can be provided by many compounds including an antifoamant of the polysiloxane type, for example, silicone oil or polydimethyl siloxane.

Some of the above-mentioned additives can provide a multiplicity of effects; thus, for example, a single additive may act as a dispersant-oxidation inhibitor. This approach is well known and does not require further elaboration.

Illustrative, non-limiting examples of additives specific to use in compression refrigeration systems follow.

Extreme pressure additives are known to those skilled in the art, and are used to provide protection for metal surfaces in applications that occur under relatively very high pressures. Illustrative extreme pressure and antiwear additives include phosphates, phosphate esters (bicresyl phosphate), phosphites, thiophosphates (zinc diorganodithiophosphates) chlorinated waxes, sulfurized fats and olefins, organic lead compounds, fatty acids, molybdenum complexes, halogen substituted organosilicon compounds, borates, organic esters, halogen substituted phosphorous compounds, sulfurized Diels Alder adducts, organic sulfides, compounds containing chlorine and sulfur, metal salts of organic acids.

Illustrative oxidation and thermal stability improvers include sterically hindered phenols (BHT), aromatic amines, dithiophosphates, phosphites, sulfides and metal salts of dithio acids.

Illustrative corrosion inhibitors include organic acids, organic amines, organic phosphates, organic alcohols, metal sulfonates and organic phosphites.

Viscosity index is the measure of the change in viscosity with temperature, and a high number suggests that the change in viscosity with temperature is minimal. In view of the high viscosity index of the lube oil compositions of the present invention, it is possible to formulate a lube oil composition which is free of viscosity index improver. However, there may be applications where it is desirable to further improve viscosity index. Illustrative viscosity index improvers include polyisobutylene, polymethacrylate and polyalkylstyrenes.

Illustrative pour point and or floc point depressants include polymethacrylate ethylene-vinyl acetate copolymers, succinamic acid-olefin copolymers, ethylene-alpha olefin copolymers and Friedel-Crafts condensation products of wax with napthalene or phenols.

Illustrative detergents include sulfonates, long-chain alkyl substituted aromatic sulfonic acids, phosphonates, thiophosphonates, phenolates, metal salts of alkyl phenols, alkyl sulfides, alkylphenol-aldehyde condensation products, metal salts of substituted salicylates, N-substituted oligomers or polymers from the reaction products of unsaturated anhydrides and amines and co-polymers which incorporate polyester linkages such as vinyl acetate-maleic anhydride co-polymers.

Illustrative anti-foaming agents are silicone polymers.

Illustrative viscosity adjusters include polyisobutylene, polymethacrylates, polyalkylstyrenes, naphthenic oils, alkylbenzene oils, paraffinic oils, polyesters, polyvinylchloride and polyphosphates.

In the present invention, the additive(s) should be at least partially (greater than about 50% by weight) miscible in the base stock. Generally, this means that the additives used will be oil soluble at least to some extent, and preferably to a substantial extent.

The lube oil composition should thus preferably be a substantially uniform mixture, with substantially no settling or phase separation of components.

The lubrication oil composition preferably comprises the additives in an amount of less than 50 wt %, based on the total weight of the lubrication oil composition. In various embodiments, the lubrication oil can comprise the additives in an amount of about 25 wt % or less, or about 10 wt % or less, or about 5 wt % or less, based on the total weight of the lubrication oil composition.

Specific Additive Package

In some embodiments, the lubrication oil compositions contain an additive package comprising a combination at least three different additives (wt % is based on total composition weight):

(a) an antiwear additive package comprising from about 0.5 to about 2.0 wt % of a mixture comprising an amine phosphate antiwear additive and a phosphorothionate antiwear additive, and

(b) from about 0.05 to about 0.5 wt % of methylene bis(dialkyldithiocarbamate). The methylene bis(dialkyldithiocarbamate) can function as an extreme pressure additive and/or an antioxidant.

In alternate embodiments, the antiwear additive package in the lubrication oil composition contains from about 0.5 to about 1.0 wt % of a mixture comprising an amine phosphate antiwear additive and a phosphorothionate antiwear additive.

In alternate embodiments, the additive package contains from about 0.1 to about 0.3 wt % of the methylene bis(dialkyldithiocarbamate).

In a preferred embodiment, the lubrication oil compositions further comprise one or more of the following (wt % is based on total composition weight):

(c) from about 0.05 to about 2.0 wt %, or alternatively from about 0.05 to about 1.0 wt %, or alternatively from about 0.1 to about 0.5 wt %, of a tolutriazole antioxidant/metal passivator additive; and/or

(d) from about 0.05 to about 1.0 wt %, or alternatively from about 0.1 to about 1.0 wt %, or alternatively from about 0.1 to about 0.75 wt %, of a primary antioxidant additive package selected from the group consisting of a hindered amine antioxidant, a hindered phenol antioxidant and a mixture thereof, and/or

(e) from about 0.05 to about 0.3 wt %, or alternatively from about 0.05 to about 0.2 wt %, of a calcium sulfonate corrosion inhibitor; and/or

(f) from about 0.01 to about 2.0 wt %, or alternatively from about 0.05 to about 1.0 wt %, or alternatively from about 0.1 to about 0.5 wt %, of one or a combination of a thiadiazole metal passivator and a disulfide metal passivator.

Gear/Hydraulic Lubricants

A preferred use of the lubricant compositions of the present invention is as a gear/hydraulic lubricant. An exemplary formulation for such a lubricant is as follows (wt % is based on total composition):

(a) from about 90 to 99 wt %, or alternatively from about 95 to about 98.5 wt %, of a PTEEG that is fluid at ambient temperature, or a mixture of a PTEEG and PTEEG ester that is fluid at ambient temperature;

(b) an antiwear additive package comprising from about 0.5 to about 2.0 wt %, or alternatively from about 0.5 to about 1.0 wt %, of a mixture comprising an amine phosphate antiwear additive and a phosphorothionate antiwear additive;

(c) from about 0.05 to about 0.5 wt %, or alternatively from about 0.1 to about 0.3 wt %, of a methylene bis(dialkyldithiocarbamate) extreme pressure/antioxidant additive;

(d) from 0 to about 2.0 wt %, or alternatively about 0.05 to about 2.0 wt %, or alternatively from about 0.05 to about 1.0 wt %, or alternatively from about 0.1 to about 0.5 wt %, of a tolutriazole antioxidant/metal passivator additive;

(e) from 0 to about 1.0 wt %, or alternatively from about 0.05 to about 1.0 wt %, or alternatively from about 0.1 to about 1.0 wt %, or alternatively from about 0.1 to about 0.75 wt %, of a primary antioxidant additive package selected from the group consisting of a hindered amine antioxidant, a hindered phenol antioxidant and a mixture thereof,

(f) from 0 to about 0.3 wt %, or alternatively from about 0.05 to about 0.3 wt %, or alternatively from about 0.05 to about 0.2 wt %, of a calcium sulfonate corrosion inhibitor; and/or

(g) from 0 to about 2.0 wt %, or alternatively from about 0.01 to about 2.0 wt %, or alternatively from about 0.05 to about 1.0 wt %, or alternatively from about 0.1 to about 0.5 wt %, of one or a combination of a thiadiazole metal passivator and a disulfide metal passivator.

EXAMPLES

All parts, percentages, etc., are by weight unless otherwise indicated.

ASTM method D445-83 and ASTM method D792-91 were used to determine the kinematic viscosity and density of the polymer, respectively.

Additional ASTM methods were used as listed in the Tables below.

The materials of the present invention were tested with and without a lube oil additive package. The package used during the testing comprised the components listed in Table 1.

TABLE 1 Additive Description Function Available From IRGALUBE ® Triphenyl phosphorothionate, Anti- Ciba Specialty TPPT typically wear/extreme Chemicals, containing 9% pressure Tarrytown, NY phosphorus and 9.4% sulfur VANLUBE ® Methylene Ashless anti- R T Vanderbilt 7723 bis(dibutyldithiocarbamate) oxidant and extreme Company Inc., pressure Norwalk, CT VANLUBE ® Tolutriazole Antioxidant R T Vanderbilt 887E Company Inc., Norwalk, CT PANA Phenyl a- Antioxidant Akrochem, Akron, naphthalmine OH VANLUBE ® Polymerized 1,2- Antioxidant R. T. Vanderbilt RD dihydro-2,2,4- Co., Inc., Norwalk, trimethylquinoline CT IRGANOX ® Hindered phenol Antioxidant Ciba Specialty 1135 Chemicals, Tarrytown, NY IRGALUBE ® Mixture of amine EP/AW & corrosion Ciba Specialty 349 phosphates inhibitor Chemicals, Tarrytown, NY VANLUBE ® Calcium sulfonate Rust inhibitor R T Vanderbilt 8912E Company Inc., Norwalk, CT CUVAN ® 826 2,5 dimercapto- Corrosion inhibitor R T Vanderbilt 1,3,4-thiadiazole & metal Company, Inc., derivative deactivator Norwalk, CT IRGACORE ® Corrosion Inhibitor Ciba Specialty L12 Chemicals, Tarrytown, NY Polydimethylsiloxane Defoamer Dow Corning, polymer 200 cSt Midland, MI LUBRIZOL Ester copolymer Defoamer The Lubrizol 889D Corporation, Wickliffe, OH

Examples 1-5

Examples 1-5 were prepared by blending the solid ingredients (in pellet form) in a PTEEG (made using 25 mol % ethylene glycol) having an Mn as set forth in Table 2, either by stirring at 50° C. or rotating the mixture in an enclosed jar on a jar roller mill at room temperature, over a period of 2 to 3 days. The pellet form of the solid ingredients helped avoid air entrainment which occurred when the powder forms were used, resulting in excess foaming. When the mixtures were prepared in an open jar, a nitrogen atmosphere was used. Liquid additives were added to the premixed blends, ensuring that no solid particles were left undissolved. Table 2 below summarizes the compositions of these examples.

TABLE 2 Examples 1-5 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Polydimethylsiloxane 0.005 0.0025 0.0025 polymer Lubrizol 889D 0.05 0.05 Vanlube ® 7723 0.3 0.3 0.2 0.3 0.3 Vanlube ® 887E 0.4 0.4 0.3 0.4 0.4 Irganox ® 1135 0.2 0.2 0.2 0 Irgalube ® TPPT 0.5 0.5 0.5 0.5 0.5 Irgalube ® 349 0.4 0.4 0.4 0.4 0.4 Vanlube ® 8912E 0.1 0 PANA 0.5 0 Vanlube ® RD 0.25 0.25 0.5 0.5 Irgacore ® L12 0.1 0 CUVAN ® 826 0.1 0.1 0.1 0.1 0.1 PTEEG (Mn, 98.3 (993) 97.85 (1093) 97.95 (1093) 97 (1040) 97.8 (993) SEC/GPC)

The compositions in the Examples were subjected to the tests required for establishing the standard specifications for industrially acceptable antiwear gear/hydraulic oils. The results are shown in Tables 3 and 4.

TABLE 3 Lubricant Properties of Examples 1-5 Property ASTM Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Viscosity Index D-2270 207 206 208 203 Pour Point, ° C. D-97 −45 −45 −48 −42 −48 Flash Point, ° C. D-92 272 288 286 302 294 Four Ball Wear D-4172 0.3 0.37 0.4 0.59 0.45 Scar, mm Coefficient of D-4172 0.042 0.033 0.032 0.044 0.051 Friction Load Wear index D-2783 50.13 61.5 77 77 42.28 Last Nonseizure D-2783 126 (.49) 160 (.52) 200 (.54) 200 (.52) 100 (.43) Load (scar, mm) Last Seizure D-2783 160 kg None None None 160 kg Load (scar, mm) (2.78) (2.37) Weld Load, kg D-2783 200 200 250 250 200 Falex Pin & V D-3233 4250 3000 3000 4250 3500 block Max Load, lbs

TABLE 4 Oxidation & Corrosion Test Results (ASTM D4636-190 C.-24 h) Property Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Viscosity Change −11.7 1.49 0.97 6.731 6.5 Acid Number 0.7 0.07 0.09 0.3 0.3 Change (Mg/KOH/g) Viscosity @ 40° C. 195.1 234.8 238.3 208.1 198.1 Original, cSt, 172.2 238.3 240.6 222.1 210.9 cSt Total Acid # 0.22 0.25 0.25 0.42 0.21 Original, mg KOH/g, 0.92 0.32 0.34 0.72 0.51 mg KOH/g Copper Corrosion Dull-1b Dull-1b Dull-1b Dull-1b Dull-1b

Example 1 contained a minimal amount of antioxidants compared to other examples (as shown in Table 2). This lubricant showed signs of thermal degradation (as shown in Table 4) during Oxidation and Corrosion Test (ASTM D4636) as shown by the drop in viscosity (−11.7%) and a significant change in acid number (0.7) after operating at 190° C. for 24 h. However this composition showed excellent antiwear and load carrying properties (as shown in Table 3) as shown by the very low four ball wear scar (0.3 mm-ASTM D4172-40 kg, 1200 rpm @75° C.) and the Falex Pin and V Block test (Maximum Load 4250 lbs-ASTM D3233).

Example 2 contained an antioxidant package containing primary antioxidants including a hindered amine, VANLUBE® RD (0.25 wt %) and a hindered phenol, IR-GANOX® 1135 (0.2 wt %) in addition to the secondary antioxidant VANLUBE® 7723 (dithiocarbamate). This lubricant showed very little change in viscosity and negligible amount of acid number change as tested by ASTM D4636.

Example 3 contained a calcium sulfonate (VANLUBE® 8912E, 0.1 wt %). Coincidently, this additive package show excellent load carrying properties as shown by the high “Load Wear Index” (77) in spite of the fact that it contains lower quantity of VANLUBE® 7723.

Examples 4 and 5, containing 0.5 wt % or more of hindered amine (VANLUBE® RD & PANA), showed a high viscosity increase compared to the examples containing 0.25 wt % VANLUBE® RD, although they both showed high load carrying properties as indicated by the Falex Load (Table 3)

A negative impact on wear properties was also observed with inclusion of hindered amine in excess of 0.5% (lowest “Four Ball Wear” in the absence of VANLUBE® RD).

A low “Coefficient Of Friction” was observed at a VANLUBE® RD level of 0.25 wt %, regardless of other components.

The compositions of the invention provide high load carrying capability (Falex Load>3000 lbs—Table 3), low coefficient of friction and wear.

Also, the antioxidant combination of hindered phenol and hindered amine provided the best results for oxidation and thermal stability, corrosion and rust resistance (Copper Corrosion-1b) as shown in the Examples.

Compositions containing 0.25 wt % VANLUBE® RD (hindered amine) and 0.2 wt % IRGANOX® 1135 (hindered phenol) showed minimal viscosity and acid number change for the Oxidation and Corrosion Stability test—ASTM D 4636@190° C.—24 h. 

1. A lubrication oil composition comprising: (i) a base fluid stock comprising a poly(trimethylene-ethylene ether)glycol that is fluid at ambient temperature, and (ii) an additive package comprising: (a) an antiwear additive package comprising from about 0.5 to about 2.0 wt % (based on total composition weight) of a mixture comprising an amine phosphate antiwear additive and a phosphorothionate antiwear additive, and (b) from about 0.1 to about 0.5 wt. % (based on total composition weight) of an additive that functions as an extreme pressure additive, as an antioxidant additive, or as an extreme pressure additive and an antioxidant additive.
 2. The lubrication oil composition of claim 1 wherein the additive that functions as an extreme pressure additive, as an antioxidant additive, or as an extreme pressure additive and an antioxidant additive is a methylene bis(dialkyldithiocarbamate).
 3. The lubrication oil composition of claim 1, wherein the additive package further comprises at least one selected from the group consisting of: (c) from about 0.05 to about 2.0 wt % of a tolutriazole antioxidant/metal passivator additive; (d) from about 0.05 to about 1.0 wt % of a primary antioxidant additive package selected from the group consisting of hindered amine antioxidants, hindered phenol antioxidants and mixtures thereof, (e) from about 0.05 to about 0.3 wt % of a calcium sulfonate corrosion inhibitor; and (f) from about 0.01 to about 2.0 wt % of at least one selected from thiadiazole metal passivators and disulfide metal passivators.
 4. The lubrication oil composition of claim 3, wherein the additive package comprises from about 0.1 to about 0.5 wt % of a tolutriazole antioxidant/metal passivator additive.
 5. The lubrication oil composition of claim 3, wherein the additive package comprises from about 0.1 to about 0.75 wt %, of a primary antioxidant additive package selected from the group consisting of hindered amine antioxidants, a hindered phenol antioxidants and mixtures thereof.
 6. The lubrication oil composition of claim 3, wherein the additive package comprises from about 0.05 to about 0.2 wt %, of a calcium sulfonate corrosion inhibitor.
 7. The lubrication oil composition of claim 3, wherein the additive package comprises from about 0.1 to about 0.5 wt % of at least one selected from thiadiazole metal passivators and disulfide metal passivators.
 8. The lubrication oil composition of claim 1, wherein the additive package further comprises a tolutriazole antioxidant/metal passivator additive in an amount of from about 0.05 to about 2.0 wt % (based on total composition weight).
 9. The lubrication oil composition of claim 1, wherein the additive package further comprises from about 0.05 to about 1.0 wt % (based on total composition weight) of a primary antioxidant additive package selected from the group consisting of a hindered amine antioxidant, a hindered phenol antioxidant and a mixture thereof.
 10. The lubrication oil composition of claim 1, wherein the additive package further comprises from about 0.01 to about 2.0 wt % (based on total composition weight) of one or a combination of a calcium sulfonate corrosion inhibitor, a thiadiazole metal passivator and a disulfide metal passivator.
 11. The lubrication oil composition of claim 1 wherein the base fluid stock is about 50 wt % or greater, based on the total weight of the lubrication oil composition.
 12. The lubrication oil composition of claim 11, wherein the base fluid stock is about 75 wt % or greater, based on the total weight of the lubrication oil composition.
 13. The lubrication oil composition of claim 11, wherein the base fluid stock is about 95 wt % or greater, based on the total weight of the lubrication oil composition.
 14. The lubrication oil composition of claim 1, wherein the base fluid stock consists essentially of the poly(trimethylene-ethylene ether)glycol.
 15. The lubrication oil composition of claim 1, wherein the base fluid stock comprises a mixture of the poly(trimethylene-ethylene ether)glycol and a poly(trimethylene-ethylene ether)glycol ester.
 16. The lubrication oil composition of claim 1, wherein said lube oil additive is at least 50% miscible in the base fluid stock.
 17. The lubrication oil composition of claim 1, wherein said lube oil composition a substantially uniform mixture, with substantially no settling or phase separation, of the components.
 18. The lubrication oil of claim 1, wherein the poly(trimethylene-ethylene ether)glycol has a number average molecular weight of at least about 250 to less than about
 10000. 19. The lubrication oil composition of claim 1, wherein the poly(trimethylene-ethylene ether)glycol is prepared from biologically produced 1,3-propane diol. 